The following paragraphs are not an admission that anything discussed in them is prior art or part of the knowledge of persons skilled in the art.
There are known a number of umbrella designs. These are used to protect a user from rain, sun and and/or wind. A conventional umbrella has a rigid central shaft and a plurality of ribs or spokes attached to the top of the central shaft. Supporting struts or connecting ribs connect the ribs or spokes to a slider on the central shaft. The frame of the umbrella is thus movable between open and closed configurations, but each rib or spoke is of fixed dimensions, and is usually of one piece construction.
Other umbrella designs are described as compact or multiple fold, and sometimes as collapsible. They have ribs that have a two or more rib elements pivotally connected together, and usually the central shaft has two or more elements that telescope together, so that when collapsed or folded, the umbrella is smaller and more compact.
For all these known umbrella designs, the ends of the ribs are generally perpendicular to the periphery of the canopy and are exposed. Even if the ribs are rounded or otherwise provided with protective elements, they still can be a nuisance to others and a danger to people's eyes.
U.S. Pat. Nos. 5,394,896 and 5,305,771 to Peter Wilk discloses a frame for an umbrella that has ends of the ribs connected together by curved elements, intended to eliminate the problem of the tips of the ribs protruding beyond the canopy. However, this patent fails to recognize that in a collapsed or folded configuration, the effective radius of the ribs is increased beyond the effective radius in the open configuration. This proposal does not have the edge or periphery of the canopy attached to the frame at any point.
A more recent proposal is disclosed in published PCT application WO 2005/048765 (Brebner). It provides a complex arrangement, in which the ribs have rods sliding within tubes, to actuate force spreading components at the ends of the ribs.
An example of an asymmetric umbrella is disclosed in published PCT application WO2006/132525 (Senz Technologies B.V.). The entire content of all the patents and published applications disclosed herein are hereby incorporated by reference.